Chamber temperature is lower than 0°C. It happens when build-plate temperature sensor is broken or its cable is broken.
a. Re-plug J62 in main board, check if the cable of chamber temperature sensor was broken in somewhere.
b. Unplug J62 in main board, measure the resistance via pin 1&2, it should be around 110KΩ @ 25°C indoor temperature. Figure 04-1. If the resistance is close to 0Ω, replace the sensor and its cable.